1. Field of the Invention
The present application relates to a patterned retarder type stereoscopic image display device, and more particularly, to a patterned retarder type stereoscopic image display device with increase vertical viewing angle and decreased the light leakage.
2. Discussion of the Related Art
Recently, due to developments of various video contents, stereoscopic image display devices which the user can select the display type (two- or three dimensional) has been introduced. The three-dimensional display can be accomplished using the stereoscopic technique or the autostereoscopic technique.
The stereoscopic technique uses a binocular disparity due to a separation distance between the eyes. This type can be divided into the glasses type and the glasses-free type. Among the glasses type, there is a stereoscopic image display device where a patterned retarder is disposed on a display panel. This type of device accomplishes three-dimensional display using polarization properties of the patterned retarder on the display panel and those on the glasses. They have advantages in having small cross-talk between two eyes and in having good display quality of high brightness compared to other types.
At this time, the display panel for displaying both two-dimensional and three-dimensional images can be one of the various flat panel display devices such as the liquid crystal display (LCD) device, the field emission display (FED) device, the plasma display panel (PDP), the Electrophoresis (EPD), or the electroluminescence device (EL) including the inorganic electroluminescence device and the organic light emitting display (OLED) device.
As one example, a display panel of an LCD device will be explained. FIG. 1 is a schematic view of a patterned retarder type stereoscopic image display device according to the related art.
As shown in FIG. 1, the display device 1 has a display panel 20 for displaying a two-dimensional image or three-dimensional image and a patterned retarder 17 attached to the display panel 20. The display panel includes an array substrate 10 and a color filter substrate 12 having a color filter 13 and a black matrix 14, a liquid crystal layer 15 between the array substrate 10 and the color filter substrate 12, and first and second polarizing plates 16a and 16b attached to the color filter substrate 12 and to the array substrate 10, respectively. The patterned retarder 17 is attached to the first polarizing plate 16a, and has a first retarder for selectively transmitting only first polarizing light and a second retarder for selectively transmitting only second polarizing light. The first and second retarders are formed line-by-line in turns. At this time, a protection film 18 may be formed on the patterned retarder 17.
The display device 1, as described, alternately displays a right-eye image and left-eye image on the display panel, and switches the polarizing properties from the polarizing glasses though the patterned retarder 17. The viewer combines the transmitted-left-eye and the right-eye images respectively and realizes a three-dimensional stereoscopic image.
When the three-dimensional stereoscopic image is accomplished, a three-dimensional (3D) cross-talk can occur according to the viewing positions. That is, when users see the display panel in up- and down direction, the left-eye image may pass not only the first retarder but also the second retarder and get mixed with the right-eye image. And similarly, the right-eye image may become mixed with the light-eye image.
By enlarging the width of the black matrix, the viewing angle can be broadened and the 3D cross-talk can be prevented from occurring. However, this method results in lowering the opening aperture ratio and brightness of the front side. Thus, the display becomes dark and proper chroma is difficult to obtain.
Meanwhile, a light leakage problem generally exists in the display panel. Light from the backlight unit leaks around the front or side of the display panel. To solve the problem, additional black matrix is formed on the non-active area of the display panel. To fulfill the purpose, it is necessary that the black matrix satisfy insulation characteristics, or that a dielectric constant should be below 3.0. However, pigment for the black matrix is generally carbon black, which does not have enough insulation characteristics. Thus, although it is possible to lower reflection of the light, passing of light cannot be blocked.
In order to solve the above problem, black column spacers are formed on the non-active area of the display panel instead of the black matrix. But, manufacturing cost becomes high and the adhesion of the array substrate and the color filter substrate is not so good.